Fluid pressure brake



De- 17, 1935 E. E. HEwlTT ET AL FLUID PRESSURE BRAKE Filed Feb. 24, 1931 w33 me .omSu .Sn .uo mzm... non L .w15 o: E. .2. no mzwt. mon.

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m b l() INVENTORS ELLIS EHEVVITT AND CLYDE C FARMER Qf/.d/

ATTORNE Veo Patented Dec. 17, Y1935 UNITED 5T FLUID PRESSURE BRAKE Ellis IE. Hewitt, Edgewood, and Clyde C. Farmer, Pittsburgh, Pa., assignors to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporaticn ef Pennsylvania Appiicaticn February 24, 1931, Serial No. 517,660

33 Claims.

This invention relates to fluid pressure brakes and moreparticularly to the type in which the brakes are applied by effecting a reduction in a result, Vthe brakes on the train apply serially Y from the front 'toward the rear and seti up a retardation which causes the slack in the train to run in which often results in excessive shocks.

One object oi our invention is to provide improved meansY for delaying or holding back the application of brakes on the locomotive, Vso that the inertia of the locomotive will tend to keep the slack in the train pulled out and thus avoid excessive shocks.

Another object of our invention is to provide improved means for delaying or holding back the application of brakes on the locomotive for a period of time, after the initiation of a brake pipeV reduction, which Vis proportional to the Ylength of the brake pipe on a train.

Other objects and advantages will appear in the following more detailed description ofV our invention. Y Y

In the accompanying drawing; Fig. 1 is a diagrammatic view, mainly in section, of a locomotive brake equipment having Vour invention associated therewith; Fig. 2 is a diagrammatic View of a portion of the distributing valve device shown in Fig. l, but With a plug valve shown in a cut out position; Fig. 3 is a development view showing diagrammaticallythe connections established in Various positions of the brake valve device shown in Fig. Vi; Vand Fig. 4 is a diagrammatic development View of the manually operated timing control Valve device shown inFig. 1. Y Y f y As shown in the drawing, the locomotive brake equipment comprises a brake controlling vvalve device, such as a distributing valve device l, an automatic brake valve device 2 for Vcontrolling the operation of said distributing Valve device, a hold back valve Vdevice 3, a timing control valve device a main reservoir 5, an equalizing reservoir ii, a feed valve device i, and a brake cylinder Y Y The distributing valve devicey comprises a casing containing the usual equalizing portion and application. portion. The equalizing portion comprises a'piston S having at one side a charnberY I0 andat the other side a *Valve ciiiarnberY A l! containing a main slide valve I2 and an auxiliary slide valve I 3 adapted to beroperated by 'said piston,.the chamber II being in constant communication with a pressure chamber It.

The application portion of the distributing valve device comprises a piston I5 having at one side a chamber it and at the other'side a chamber I'I open to the brake cylinder 8 through a passage and pipe I3. Extending to the right from piston i5 and through a Valve chamber I9 is a piston stem 2E) having mounted thereon a bafie piston 2l separating chambers I'IrandV I9. An exhaust slide valve 22 is disposed in chamber i9. between spaced shoulders 23 on the stem 2Q and Vis adapted to be operated thereby. Projecting upwardly from the stem 20 is a driving pin 24 operatively engaging an application slide valve i5 contained in a chamber 26.

The automatic brake valve device Z comprises a casing having a chamber 2'! containing a rotary valve 28 adapted to be turnedV to va-V Y rious controlling positions by a handle 29' operatively connected to said rotary valve by means of a stem 39. Disposed in theA brake valve casing is the usual brake pipe discharge valve mechanism comprising an equalizing piston 3| having at Vone side a chamber 32 connected to the equalizing reservoir 6 through a passage and Ypipe 34. The equalizing piston 3l has at the other side a chamber 35 connected to the brake pipe 36 through passage and Ypipe Y3l, and containinga brake pipe discharge Valve 33 adapted to be operated by said piston. Y

In the'usual locomotive brake equipment, the distributing valve device I operates in accordance with variations in brake pipe pressure, but as shown in the drawing, the hold back valve device 3 is interposed between the distributing valve device I and brake pipe 35 for controlling theV operation of the distributing Valve device, as

will hereinafter be fully described. v

The hold Vback valve device 3 comprises a control valve portion anda timing valve portion.

ber or volume reservoir 5B is connected by pas-4 sage 4l to chamber 46 for increasing the volume of said chamber. Y

The timing valve portion of the hold back valve device 3 comprises a flexible diaphragm 5I mounted in the casing and having at one side a chamber 52 and at the other side a valve chamber 53 which is in constant communication with the atmosphere through a choke plug 54. The chamber 53 contains a slide valve 55. adapted to be operated by deflection of said diaphragm. Projecting into valve chamber 53- is a spring-pressed member 56; adapted to engage the diaphragm stem 51 for opposing deflection of said diaphragm. The slide valve 55 is pressed into engagement with its seat by means of a spring pressed roller 58.

The diaphragm chamber 52 of the timing valve portion of the hold back device 3 is connected to the seat of the control valve slide valve 48 by means of a passage 5), and said passage has a branch leading to a plug valve 59. In the normal position of plug valve 60, a port 6I in said plug valve connects passage 59 to a passage 62 leading to a timing reservoir 63. In the cut out position of said plug valve, shown in Fig. 2, passage 59 is disconnected from passage 62, but another port 64 in said plug valve is adapted to connect passage 65 leading to the seat of slide valves 4.8 and 55 to an atmospheric passage 55, this latter connection being closed in the cut in position shown in Fig. 1. The plug valve 69 is adapted to be operated from one position to the other position by a handle 61.

The timing control valve device 4 comprises a casing having a chamber 39 containing a rotary valve 45 adapted to be operated by a handle 4I through the medium of an operating member 42.

In operation, to initially charge the brake equipment with fluid under pressure, fluid under pressure is supplied to the main reservoir 5 by an air compressor in the usual well known manner and flows therefrom through pipe 68 to the distributing valve device I, to the feed valve device 1 and to the brake' valve device 2 and from said pipe through passage 69 to the rotary valve chamber 21 of the brake valve device 2.

In charging the brake pipe 36, it is customary for the engineer to first move the brake valve device to release position in which the brake pipe passage 31 is connected directly to valve chamber 21 so that fluid at main reservoir pressure is supplied to the brake pipeV 36 to accelerate the charging of said brake pipe. Then after a predetermined time, the brake valve device is turned to running position shown in Fig. Y1.

The feed valve device 'i' is adapted to reduce the pressure of fluid from that carried in the main reservoir 5 and supplied thereto through pipe 68 to that normally` carried in the brake pipe 36 and supply iluid at this reduced pressure to pipe and passage 18 leading to the seat of the brake valve rotary valve 28. 'n running position of the brake valve device, the feed valve passage 10 is connected by a cavity 1I in the rotary valve 23 to the brake pipe passage 31, so that fluid at feed valve pressure ows from passage 10 through passage 31 to the brake pipe 36, thereby charging said brake pipe.

Fluid at feed valve pressure also flows from passage 31 to the equalizing piston chamber 35 and at the same time from cavity 1I in the rotary valve 28 through a passage 13 to the equallizing piston chamber 32 and from said chamber through passage and pipe Sato the equalizing reservoir 6. In this manner the equalizing reservoir 6 and chambers 32 and 35 at the two sidesV of the equalizing piston 3i become charged with fluid at brake pipe pressure and the discharge valve 38 is held seated in the usual manner.

Fluid under pressure supplied to brakeI pipe 36 in the above described manner, flows through pipe and passage 45 to the control valve piston 5 chamber 44 of the hold back valve device 3. With the control piston 43 in its inner position, as shown in the drawing, uid under pressure ows from chamber 44 through passage 14, choke 15, passage 19, past a ball check valve 11 10 and through passage 18 to the control valve chamber 49 and from thence through passage 41 to the reservoir 53, and through passage and pipe 41 to the equalizing piston chamber IS of the distributing valve device I. With the equalizing 15 piston 9 in its release position, a feed groove 19 is uncovered which permits fiuid under pressure to now from piston chamber I@ to valve chamber II and from thence through passage to pressure chamber I4. In this manner the pres- 20 sure chamber I 4, valve chamber II, piston chamber lil, reservoir 5S and control valve chamber 46 are charged with uid at brake pipe pressure.

Fluid under pressure also flows from passage 25 14 in the hold bacia valve device through a lchoke 8|, passage 82, cavity 83 in the control valve slide valve 48 and passage 59 to the timing valve diaphragm chamber 52 and from passage 59 through port BI in the plug valve @D and 30 passage 52 to the timing reservoir 53 so that said chamber and reservoir also become charged with fluid at brake pipe pressure. The pressure of fluid in diaphragm chamber 52 defiects diaphragm 5i to the left until the follower plate 35 84 on the diaphragm stem 51 engages the casing, in which position the spring-pressed member 55 is moved to the depressed position shown in the drawing. Y

With the equalizing piston 9 and slide valves 40 2 and i3 of the distributing valve device i in the normal or release position, shown in Fig. l, the application piston chamber I 6 is opened to the atmosphere through passages 85 and 86, cavity 81 in the main slide Valve l?. and passage 45 and pipe 88, said pipe being open to the atmosphere. An application chamber 89 in the distributing valve device is open through passage 99 to the vented cavity 31 in the main slide valve I2 and therefore is also normally at atmos- 50 pheric pressure.

A service application of the brakes is effected in the usual manner by turning the brake valve device 2 to service position in which the brake pipe passage 31 is lapped by the rotary valve 55 28, so as to prevent further ow of uid under pressure from the feed valve device 1 to the brake pipe 39 and at the same time the equalizing piston chamber 32 and the connected equalizing reservoir 6 are connected to the atmos- 60 phere through passage 13, a cavity in the rotary valve 28, and an atmospheric passage 94, thereby permitting the pressure of fluid in the piston chamber 32 to reduce below the brake pipe pressure in chamber 35. Upon such a reduction, the 65 brake pipe pressure in chamber 35 moves the equalizing piston 3i upwardly, which pulls Ythe brake pipe discharge valve 38 away from its seat and permits fluid under pressure to oW fromy the brake pipe 39 to the atmosphere by way of "0 Vpipe and passage 3l, chamber 35 and past the open discharge valve 3S. If it is desired to limit the degree of reduction in brake pipe pressure, the brake valve device is turned from service position to lap position when the desired degree 75 of reduction is effected in the equalizing reservoir pressure acting in chamber. 32. After the reduction in chamber 32 is thus stopped, the brake pipe pressure in chamber 35 continues to reduce until it becomes substantially equal to or slightly less than the pressure in chamber 32, at which time the equalizing piston 3l seats the discharge valve 38 in the usual manner, and

thereby prevents any further reduction in brake pipe pressure.

As the pressure of uid in the brake pipe V3b is reduced, a corresponding reduction occurs in the control valve piston chamber Ui of the hold back valve device 5.V The rate of reduction in pressure in chamber i4 exceeds the capacity of the serially arranged chokes Hu and 'i5 to vent iiuid under pressure from chamber li@ to chamber 44 to such an Vextent that a sui'li-cient diierential 1 of pressures is obtained on the control piston i3 to shift said piston and slide valves 48 andi?! to application position in Which a port 95 in the main slide valve 48 isV uncovered by the auxiliary slide valveV ligand said port registers With the passage 65 which leads to the seat of the timing valve slide valve 55 and is normally lapped by said slidervalve. v 4

In 'application position of the control valve slide valve 43, passage 59Vis connectedthrough cavity 95 to a. passage 8l which is open to the atmosphere through passageand pipe. 98, cavity 99 in rotary valve 45 of the timing control valve device 4 and a choke plug itil. This permits uid under pressure to gradually flow from the diaphragm chamber 52 and timing reservoir 63' to the atmosphere lat a rate governed by the iiow area of choke plug mi). When the pressure of fiui'd in diaphragm chamber 52 is thusreduced to a predetermined degree, the pressure of spring I0! acting through member 56 shiftsthe stem 51 and slide valve 55 and delects the diaphragm 5i to application position, in which the diaphragm engages a limiting stop 52. Y

With the timing valve slide valve 55 in application position, passage E5 is uncovered and connected to the valve chamber 53. Passage 65 is also connected through port 95 in the control slide valve 43 to a valve. chamber :i5 which is in communication with chamber 5i) and equalizing piston chamber IB of the distributing valve device. As a result, uid under pressure is permitted to flow from the equalizing piston chamber lil and chamber 5E! to the timing valve chamber 5.3 and from thence through the choke'plug 54 to the atmosphere. This reduces the pressure in chamber lil vand permits the pressure of fluid vided merely'to increase thevolume ci the appli- Y cation piston chamber l5.

The pressure oi fluid in the application piston chamber it shifts the application` piston l5 and slide valves 22 and 25 towardfthe right to appli.- cation position in which the slide valve 22 laps the exhaust passage 32 and the port 555 in the slide Valve. 25 establishes communication be,- tween chambers 26 and i9.k This permits fluid under pressure supplied from the main reserton 9 Which would undesirably move said piston .piston t and slide valve i3 Will be moved to lap voir 5 'through pipe and passage 68 to application valve chamber 25 to iiow to valve chamber I9 and from thence through passage and pipe i8 to the brake cylinder ii, andA thereby effect an application of the brakes. 5

Y The oW capacity or" the choke plug 54 in the hold -back valve device 3 is such as tcpermit the pressure in the equalizing piston chamber Iii to reduce at a service rate, so that when the equalizing piston 9 and slide valves i2 and I3 move to service position, the venting capacity of the service port 03 will reduce the pressure in valve chamber Il at a rate sufficient to prevent a difierential from building up on the equalizing pisto emergency position in Which a high pressure- Would be quickly obtained in the brake cylinder, as will be hereinafter described. If the degree of brake pipe reduction is limited by operation of the brake valve device as herein- 20 before described, then the control piston and slide valve i9 Will remain in the right hand or application position only until the pressure in chamber 5@ and in the equalizing piston chamber I@ has been reduced through operation'of the V25 timing valve portion of the hold back valve device to a degree substantially equal to or slightly less than the reduced brake pipe pressure. When the pressure in the control valve chamber i6 is thus reduced to a degree slightly less than 30 the reduced brake pipe pressure in piston chamber 44, the piston 43 and auxiliary slide valve 49 are moved toward the left to lap position in Which'said slide valve laps port 95 and thus prevents further reduction of pressure to occur in reservoir 5B and piston chamber it.

If the reduction in piston chamber it is thus limited, the pressure in valve chamber ii will only reduce a corresponding degree and then the 40 position in which port 83 is lapped, vthereby Y limiting the degree of pressure cbtained in the application piston chamber i5. Fluid at brake cylinder pressure in passage I3 oWs to chamber il between the application 4:5

piston I5 and bafe piston 2 i, and when the pres- Y sure in said chamberV builds up to a degree slightly greater than the pressure in chamber i 6, the'piston l 5 is shifted toward the left. rlhis movement of piston i6 shifts the application slide valve 25 to lap position in Which the iiow of uid under pressure to v'alve chamber i9 and brake cylinder 8 is cut oif, thereby limiting the degree ofY brake cylinder pressure. It will thus be apparent that if the brake pipe pressure is 55 reduced in steps, the brake cylinder pressure will build up in steps. However, it should be noted that there will be no delay in applying the locomotive brakes in successive applications of the brakes after the initial partial application cf the brakes has been effected. The reason for this is that in lap position of the control portion of the hold back valve device 3, the main slide valve remains in application position in which diaphragm chamber 52 is maintained open to the atmosphere. As a result, upon a further re-- duction in. brake pipe pressure in the ccntrol piston chamber di, the control piston i3 wili merely move theauxiliary slide valve t9 so as to uncover the port 95 which Will immediately permit fluid under pressure to be further vented from chamber 55 and the application. piston Ychamber it, and thus cause a further'application v of the brakes.

It will be noted that when a brake application is initiated, the application of the locomotive brakes is delayed for a period ofV time which is governed by the blow down time of the timing reservoir 63 and the connected diaphragm chamber 52 through the choke plug |00 in the timing control valve device 4.

The length of time that the application of locomotive brakes should be delayed is greater for a long train than it is for a short train, since it takes longer to get the brakes at the rear end of a long train applied so as to stop the running in of slack. As a result, this delay time should be varied in accordance with the length of the train.

The timing control valve device has been provided for varying the delay period between the initiation of a brake pipe reduction and the applying of the locomotive brakes in proportion to the length of the train. For the purpose of illustration, the seat of the rotary valve 40 is provided with a plurality of choke plugs such as |00, |01, |08 and |09 of different sizes and in different positions in the rotary valve seat, and the cavity 99 in the rotary valve 40 is adapted to connect the passage 98 to some one of these choke plugs in accordance with its position. As shown in Fig. l, passage S8 is connected to choke plug |00 which is the proper size for timing the reduction in pressure in the timing reservoir 63 to cause the desired delay period for trains, of say 140 ears length or over. If the train length is cars or less, then the cavity 99 in rotary valve 40 will be turned to connect pipe 98 to choke plug I 69 which has a larger flow area than choke plug |00 and will consequently provide a shorter delay period.

For illustration, there are only four choke plugs shown in the timing control valve device, said chokes corresponding to four different train lengths. It is obvious that if desired, the number of choke plugs employed could be varied for any number of different increments of train length, and if desired the timing control valve device 4 could be designed so as to vary the delay time in proportion to the train length instead of in proportion to increments of train length as illustrated.

If the brake valve device 2 is moved to emergency position, the brake pipe 31 is connected directly to the atmospheric port 94, which permits a sudden reduction in brake pipe pressure to occur so as to cause an. emergency application of the brakes. This sudden reduction in brake pipe pressure permits the pressure in the control valve chamber 46 to move the control piston 43 and slide valves 48 and 49 to their right hand or application position, in which the locomotive brakes are applied in a manner similar to when a service application of vthe brakes is effected. After the delay period caused by the restricted reduction in pressure in diaphragm chamber 52 and the timing reservoir 63, the timing valve slide valve 55 is shifted to application position, in which the pressure of fluid in chamber 50 and the equalizing piston chamber I0 is permitted to reduce at a service rate and thus cause the equalizing portion of the distributing Valve device to move to service position and supply iiuid under pressure to the application piston chamber l@ and chamber 89 and cause the locomotive brakes to apply in the manner hereinbefore described.

Since in effecting an emergency application of the brakes, fluid under pressure is completely vented from the control valve piston chamber 44, the piston 43 and auxiliary valve 49 do not move to lap position as in effecting a service application of the brakes, but instead remain in the outer position in which fluid under pressure is completely ventedfrom the reservoir 50 and 5 cqualizing piston chamber I0 at a service rate. Then, after the pressure of fluid in pressure chamber I4 and valve chamber II of the distributing valve device equalizes into the application piston chamber I6 and application chamber 10 89 and the pressure of fluid in piston chamber I0 reduces below the equalized pressure in valve chamber II, the piston 9 and slide valves I2 and I3 move to emergency position, in which piston 9 engages a gasket II2. In emergency 15 position, passage 86 from the application piston chamber is connected through a cavity II3 to a passage I I4 leading to a safety valve I I5 which operates in the usual manner to limit the pressure of uid acting in the application piston 20 chamber I6, for the following reason.

When the brake valve device is moved to emergencypositioma passage I|6 is connected to the rotary valve chamber 21 through a restricted port in the rotary valve 28, which permits a25 limited flow of fluid under pressure to passage and pipe II6 leading to the seat of the timing valve slide valve 55 in the hold back valve device 3. When the timing slide valve 55 is moved to its right hand or application position for vent- 30 ing fluid under pressure from the equalizing piston chamber I0, fluid under pressure is supplied from passage II6 through cavity III in said slide valve and passage and pipe II2 to passage 56 and from thence through passage 85 35 to the application piston chamber I6. At the same time fluid under pressure is being supplied to the piston chamber I6 by operation of the equalizing portion of the distributing valve device, but this additional supply augments the 40 rate of build up in said chamber and after equalization of fluid under pressure from valve chamber II and pressure chamber I4 in the piston chamber I6 and chamber 89 and movement of the piston 9 and slide valves I2 and I3 to emer- 45 gency position, this supply of fluid from the brake valve device builds up the pressure in the application piston chamber I6 to the adjustment of the safety valve device II5 and then maintains the pressure at said adjustment against 50 any possible leakage.

It will be noted that the hold back Valve device 3 prevents the usual emergency operation of the distributing valve device I, upon a sudden reduction in brake pipe pressure, but after 5 the delay period, the rate of build up of brake cylinder pressure is faster than when a service rate of reduction is effected in brake pipe pressure, and a higher brake cylinder pressure is obtained than in service on account of the addi- (50 tional supply of fluid from the brake valve device in emergency position.

In order to release after an application of the brakes, the brake valve device 2 is turned rst to release position and then to running position 65 to charge the brake pipe 36 in the manner hereinbefore described. ThisY increase in brake pipe pressure shifts the control piston 43 and slide valves 48 and 49 to their normal orV release position shown in the drawing, in which fluid under 70 pressure is supplied from the control piston chamber 44 to the valve chamber 46 through passage 14, choke 15, past the ball check valve 11 and through passage 18. Fluid under pressure also flows from passage 14 through choke.8|, 75

4passage 32, cavity 83 in the control slide valve 48 and passage 59 to the timing valve diaphragm chamber 52 and from passage 59 through port 6I in the plug valve 66 to passage 62 leading to the timing reservoir 63, thereby charging the diaphragm chamber 52 and reservoir 63. The pressure of fluid in diaphragm chamber 52 then shifts the slide valve 35 to its normal position shown in the drawing. Y

Fluid under pressure supplied to the control valve chamber 46 flows through passage 41 to chamber 56 and through pipe and passage 41 to the equalizing piston chamber I6 of the distributing valve device. This increase in pressure in chamber I0 moves the equalizing piston 9 and slide valves I2 and I3 to release position, in which the feed groove 19 is opened by said piston so as to permit iluid under pressure to flow Vfrom piston chamber I0 to valve chamber II and from thence through passage to the pressure chamber I4 and thus charge said chambers with fluid at brake pipe pressure.

In'release position of the equalizing slide valve I2, fluid under pressure is vented from the application piston chamber I6 through passages and 86, cavity 61 in said slide Valve, .and the atmospheric passage and pipe 68. This permits brake cylinder pressure in chamber I'i at the right hand side of the application piston I5 to' shift said piston and theslide Vvalves 22 and 25` to release position in which fluid under pressure is vented from the brake cylinder 8 through pipe and passage I8, exhaust valve chamber I9 and the atmospheric passage 92, thereby effecting a lrelease ofthe brakes. Y

A choke H6, py-passing the ball check valve e 11 inV the hold back valve device, is provided to maintain substantial equalization of fluid pressures on the two sides of the control piston 43, so that when the system is charged, if a fluctuation in brake pipe pressure in piston chamber 44 occurs, as by improper operationV of the feed valve device 1, the slight reduction which may occur in piston chamber 44 will not cause undesired movement of the piston 43 and slide valves 46 and 49 to application position. 'Ihe flow area ofchoke III] is small and only sufficient to permit back Vflow from valve chamber 46 at a rate substantially equal to the rate of brake pipe pressure fluctuations. Y

In effecting a service application of the brakes, the pressure in valve chamber 46 is not completely vented and may be charged with fluid at 50l pounds pressure or more, whereas the pressure of fluid in the timing reservoir 63 is reduced to that of the atmosphere. Consequently, in releasing after an application of the brakes, there would be a tendency to first recharge the timing reservoir 63 up to the pressure in valve chamber 46 after which the pressure in the timing reservoir, the valve chamber 46, reservoir 50 and equalizing piston chamber l! would be built up together.` This would delay the -movementof the equalizing piston 9 to release position for effecting arelease of the locomotive brakes, and in order to obviate Vthis condition, the choke 3| is provided to limit the flow to the timing reservoir 63 and thus maintain sufficient pressure in passage 14 to cause a ow through choke 15. Choke 15 is provided to limit the rate of flow of fluid under pressure to valve chamber 46, chamber 56 and the equalizing piston chamber I0, so

as to prevent said chambers from becoming charged with fluid at arpressure in excess of that normally carried in the brake pipe 'during the Voir.

the brake pipe pressure reducedto that supplied by the feed valve device 1 or to even a lower pressure, the greater pressure in Valve chamber 46 would move the control piston 43 and slide valves 48 and 49 to application position and causeV an undesired application of the brakes.

If for any reason, it is desired to render the hold back valve device 3 inoperative to delay the application of the locomotive brakes upon a reduction in brake pipe pressure, lthe plug Valve 6i) is turned from the cut in position, shown in Fig. 1, to the cut out position shown in Fig. 2. In cut out position, the timing reservoir 63 is isolated from the timing valve diaphragm chamber 52V and passage 65 is opened to the Vatmosphere through port 64 in the plug valve 66 and passage 66.

if a service application of the brakes is effected with the plug valve 66 in cut out position, the control piston 43 and slide valves 48 and 46L move to application position upon a reduction in brake pipe pressure and connect the equalizing piston chamber I0, reservoir 50 and control valve chamber 46 through port 95 in control valve slide valve 48 to passage 65, which is open to the atmosphere through port 64 in the plug valve 66 and the atmospheric passage 66.

The diaphragm chamber 52 is also opened to the atmosphere through passage 59, cavity 96 in the control slide valve 48, passage 91 and passage and pipe 96 leading to the timing' control valve device 4. Since the timing reservoir 63 is cut off from diaphragm chamber 52, the timing valve diaphragm is immediately relieved of fluid pressure upon movement of the control valve which permits spring IOI to shift slide valve 55 to application position, in which fluid under pressure is permitted to iioW from passage 65 to valve chamber 53 and from thence through the choke plug 54. Thus, fluid underpressure vented through port in the control slidevalve 48 is free to flow to the atmosphere through the plug valve 66 and atmospheric port 66, as well as through the choke plug 54.

The rate at which the pressure of fluid in the equalizing piston chamber i0 reduces upon a service rate of reduction in brake pipe pressure is not governed by the venting capacity through passage 65 however, but instead, the control piston moves the main slide valve 43 to open the passage 65 an amount only suflicient to permit the pressure of fluid to reduce in valve chamber 46, reservoir 56 and equalizing piston chamber I6 at Ythe same rate as the brake pipe pressure in the control piston chamber 44 is being reduced. As a result, the distributing valve device trol valve chamber 46 shifts the control piston `43 and slide valves 4.8.and 46 to their extreme right hand or application position and maintains them in this position, in which passage 65 is wide open and permits a sudden emergency rate of reduction to occur in the equalizing piston chamber I6. This is made possible by the additional atmospheric opening from passage 65 Athrough plug Valve 60 and the atmospheric passage 66.

The emergency reduction in pressure in the equalizing piston chamber I0 permits the pressure in valve chamber Il to shift the equalizing piston 9 and slide valves l2 and I3 to emergency position, in which the piston 9 engages the gasket H2.

In emergency position of the equalizing slide valves l2 and I3, passage 86 is uncovered by the slide valve I2 and permits fluid under pressure to flow from the pressure chamber I4 and valve chamber i l to passage 86 and from thence through passage to the application piston chamber I6 and cause an emergency application of the brakes.

The pressure in the application piston chamber i6 is limited in effecting an emergency application of the brakes by the safety valve device II5, and is maintained against leakage by a supply through the brake valve device 2 when in emergency position, in the same manner as hereinbefore described.

To effect release of the brakes after an application, the brake pipe 35 is recharged and the hold back valve device 3 and distributing valve device t operate in the same manner as in releasing vflhen the plug valve 69 is in the cut in positiori.

It will now'be seen that the hold back valve device S operates upon a reduction in brake pipe pressure to delay the operation of the distributing valve device l to effect an application of the locomotive brakes for a period of time dependent upon the length of the train, as governed by the position of the timing control valve device ll, so that the brakes are applied on the rear cars of the train before the brakes are applied on the locomotive. By delaying the application of the locomotive brakes until the brakes are applied on the rear cars of the train, the inertia oi the locomotive tends to maintain the slack in the train stretched out, so that when the locomotive brakes are applied, the slack in the train will be under such control by the train brakes that excessive shocks will not occur. The hold back valve device 3 may .be rendered ineffective by turning the plug valve 50 to the cut-out position, shown in Fig. 2, in which position the locomotive brakes will operate in the usual manner.

While one Iillustrative embodiment of our invention has beenl described in detail, it is not our intention to limit its scope to that embodiment or otherwise than by the terms of the l appended claims.

Having now* described our invention, what We claim as new and desire to secure by Letters Patent, is:

l. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in fluid pres'- sure to effect an application of the brakes, and valve means operative upon eithei` a service rate or an emergency rate of reduction in brake pipe pressure" to reduce the pressure on said brake controlling valve device a predetermined time after the reduction in brake pipe pressure is initiated, said predetermined time being independent of the rate of reduction in brake pipe pressure.

2. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in fluid pressure to effect an application of the brakes, and Valve means operative upon either a service rate or an emergency rate of reduction in brake pipe pressure to reduce the pressure on said brake controlling valve device and adapted to hold back the venting of fluid pressure from said brake controlling valve device until after a predetermined time has elapsed from the initiation of said brake pipe reduction, said predetermined time being independent of the rate of reduction in brake pipe pressure.

3. In a fluid pressure brake, the combination With a brake pipe, of a brake controlling valve device operative upon a reduction in fluid pressure to effect an application of the brakes, valve means operated upon a reduction in brake pipe pressure for effecting a reduction in fluid pressure on said brake controlling valve device a predetermined time interval after the brake pipe reduction is initiated, and means for varying the time interval independently of the rate of reduction in brake pipe pressure.

4. In a uid pressure brake, the combination with a brake controlling valve device subject to the pressure of fluid and operative upon a reduction in the pressure of said fluid to effect an application of the brakes, and a brake pipe, of a valve device operative to reduce the pressure of fluid acting on said brake controlling valve device only at a service rate, and means operative upon either a service rate or an emergency rate of reduction in brake pipe pressure for causing said valve device to operate.

5. In a fluid pressure brake, the combination with a brake controlling valve device subject to the pressure of fluid and operative upon a reduction in the pressure of said fluid to effect an application of the brakes, and a brake pipe, of a valve device operative to reduce the pressure of fluid acting on said brake controlling valve device only at a service rate, and means operative upon either a service rate or an emergency rate of reduction in brake pipe pressure for causing said valve device to operate a predetermined time after the reduction in brake pipe pressure is initiated.

6. In a fluid pressure brake, the combination with an equalizing valve device operative upon a reduction in fluid pressure to effect an application of the brakes, of a timing valve device' for reducing the pressure on said equalizing valve device, a brake pipe, valve means operative upon a reduction in brake pipe pressure to cause said timing valve device to operate, and means controlled by said valve means for delaying the operation of said timing valve device for a predetermined time after the operation of said valve means.

7. In a fluid pressure brake, the combination ywith a brake pipe and a brake controlling valve device operated upon a reduction in uid pressure for effecting an application of the brakes, of control valve means operated upon a reduction in brake pipe pressure for venting fluid from said Valve device at a restricted rate and delay valve means for controlling communication through Which said control valve means vents fluid from said valve device and operated upon a predetermined reduction in fluid pressure.

8. In a fluid pressure brake, the combination With ay brake pipe and a brake controlling valve device operated upon a reduction in fluid pressure for effecting an application of the brakes, of control valve means operated upon a reduction in brake pipe pressure for venting uid from said valve device, delay valve means operated upon a predeterminedreduction in fluid pressure for opening communication through which said control valve means vents uid from said valve device, and means controlled by said control valve means for venting fluid from said delay valve means.` Y

9. In a fluid pressure brake, the combination With a brake pipe, of an equalizing valve device operated upon areduction in fluid pressure for effecting an application of the brakes, valve means operated upon a reduction in brake pipe pressure for reducing the fluid pressure on said valve device, and means for delaying the reduction in fluid pressure on said valve device only upon the initial reduction in brake pipe pressure in effecting a graduated reduction in brakeV pipe pressure.

10. In a fluid pressure brake, the combination with a brake pipe, of an equalizing valve device operated upon successiveY reductions in fluid pressure for supplying fluid under pressure to effectY a graduated application of the brakes, valve means operated upon successive reductions in brake pipe pressure, in effecting a graduated application of the brakes, for effecting corresponding successive reductions in uid pressure on said valve device, and means for delaying for a predetermined period of Vtime the initial reduction in fluid pressure on said valve device as effected by operation of said valve means upon the initial reduction in brake pipe pressure in effectingV a graduated application of the brakes.

11. In a fluid pressure brake, the combination with a brake pipe, of an equalizing valve device operated upon successive Yreductions in iluid pressure for supplying fluid under pressure to effect a graduated application of the brakes, valve means operated upon Vsuccessive reductions in brake pipe'pressure, in effecting a graduated application of the brakes, for effecting corresponding successive reductions in fluid pressure on said valve device, and means for delaying for a predetermined period of time the initial reduction in fluid pressure on said valve device as effected by operation of said valve means upon the initial reduction in brake pipe pressure, in effecting a graduated application of the brakes, succeeding reductions in fluid pressure on said valve device being effected substantially in unison with the corresponding successive reductions Yin brake pipe pressure,

12. In a fluid pressure brake, the combination With'a brake pipe and an equalizing valve device subject t'o fluid under pressure and operative upon a reduction in fluid pressure to cause an application of the brakes to be effected, of a timing reservoir normally charged with fluid under pressure, a timing valve device subject to the pressure of fluid in said timing reservoir and operative upon a reduction in pressure in said reservoir for effecting a reduction in pressure on said equalizing valve device, valve means operative upon a reduction in brake pipe pressure to vent fluid under pressure from said timing reservoir, and means for vvarying the rate atwhich fluid under pressure is vented from said timing reservoir.

13. In a fluid pressure brake, the combination with a brake pipe and an equalizing valve device subject toifluid under .pressure and operative upon a reduction in fluid pressure to cause an application` of the brakes to be effected, of a timing reservoir normally charged with iiuid under pressure, a. timing valve device subject to the pressure of fluid in said timing reservoir and operative upon a reduction in pressure in said reservoir for effecting a reduction in pressure on said equalizing valve device, valve means operative upon a reduction in brake pipe pressure to vent fluid under pressure from said timing reservoir, and valve means adjustable to correspond with the length of the train for varying the rate at which fluid under pressure is vented from said timing reservoir.

14. In a fluid pressure brake, the combination with a brake pipe and an equalizing valve device subject to fluid under pressure and operative upon a reduction in fluid pressure to cause an application of the brakes to be effected, of a timing reservoir normally charged with fluid under pressure, a timing valve device subject to the pressure of uid in said timing reservoir and operative upon a reduction in pressure in said reservoir for effecting a reduction in pressure on said equalizing valve device, valve* means operative upon a reduction in brake pipe pressure to vent fluid under pressure from said timing reservoir,

and a valve device manually adjustable for varyi ing the rate at which fluid underV pressure is vented from said timing reservoir to correspond With different lengths of train. v v

15. In a fluid pressure brake, the combination with a brake pipe and an equalizing valve device normally subject to the pressureof fluid and operative upon a reduction in fluid pressure to eifectan application of the brakes and upon an increase in fluid pressure for eiectingfa release of the brakes, of a hold back valve device operative upon an increase in brake pipe pressure to supply fluid under pressure from said brake pipe to said equalizing valve device and operative upon a reduction in brake pipe pressure to reduce the pressure acting on said equalizing valve device after a predetermined time has elapsed from the initiation of said brake pipe reduction, and means for rendering said hold back valve device inoperative to delay the reduction in pressure on said equalizing valve device upon Ya reduction in'brake pipe pressure.

16. In a fluid pressure brake, the combination With a brake pipe and an equalizing valveV device normally subject to the pressure of fluid and operative upon a reduction in fluid pressure to effect an application of the brakes and upon an `increasein uid pressure for effecting a release of the brakes, of a hold back valve means for supplying fluid under pressure from said brake pipe to said equalizing valve device upon an ine crease in brake pipe pressure and for reducing the pressure of fluid on said equalizing valve device upon a reduction in brake pipe pressure, said hold back valve means comprising a timing reservoir, a valve device operative upon an increase in brake pipe pressure for supplying fluid under pressure to. said equalizing valve device and to said timing reservoir, and upon a reduction in brake pipe pressure to cut oif said supply and connect said timing reservoir to a passage for reducing the pressure in said timing reservoir, a timing valve normally maintained in an inoperative position by the pressure of fluid in said timing reservoir, means for moving said timing valve to another position upon a reduction in uid pressure in said timing reservoir for venting fluid under pressure from said equalizing valve device, and valve means for controlling the rate of venting of fluid under pressure from said timing reservoir through said passage.

17. In a fluid pressure brake, the combination with a brake pipe, and a brake valve device having a service position for eifecting a reduction in brake pipe pressure at a service rate and an emergency position for effecting a reduction in brake pipe pressure at an emergency rate,- of a brake controlling valve device operative upon a reduction in fluid pressure to supply fluid under pressure for effecting an application of the brakes, and valve means operative either upon a service or an emergency reduction in brake pipe pressure to effect a service reduction in pressure on said brake controlling valve device, said brake valve device being operative in emergency position to supply fluid under pressure to said brake controlling valve device for augmenting the application of brakes as effected by the hereinbefore mentioned operation of said brake controlling valve device.

18. In a fluid pressure brake, the combination with a brake pipe, and a brake valve device having a service position for effecting a reductton in brake pipe pressure at a service rate and an emergency position for effecting a reduction in brake pipe pressure at an emergency rate, of a brake controlling valve device operative upon a reduction in fluid pressure to supply fluid under pressure for effecting an application of the brakes, means for limiting the pressure of fluid supplied to effect an application of the brakes, and valve means operative either upon a service or an emergency reduction in brake pipe pressure to effect a service reduction in pressure on said brake controlling valve device, said brake valve device being operative in emergency position to supply fluid under pressure to said brake controlling valve device for increasing the rate at which the brake application is effected and for increasing the pressure of the brake applying fluid.

19. In a fluid pressure brake, the combination with a brake pipe, and a brake valve device having a service position for effecting a reduction in brake pipe pressure at a service rate and an emergency position for effecting a reduction in brake pipe pressure at an emergency rate, of a brake controlling valve device operative upon a reduction in fluid pressure to supply fluid under pressure for effecting an application of the brakes, means for limiting the pressure of fluid supplied to effect an application of the brakes, and valve means operative either upon a service or an emergency reduction in brake pipe pressure to effect a service reduction in pressure on said brake controlling valve device, said brake valve device being operative in emergency position to supply fluid under pressure to said brake controlling valve device for increasing the rate at which the brake application is effected and for increasing the pressure of the brake applying fluid, the supply of fluid from said brake valve device to said brake controlling valve device being controlled by said valve means.

20. In a fluid pressure brake, the combination with a brake pipe, and a brake valve device having a service position for effecting a reduction in brake pipe pressure at a service rate and an emergency position for effecting a reduction in brake pipe pressure at an emergency rate, of a valve device movable upon a service reduction in pressure to a service position to effect a service application of the brakes and upon an emergency reduction in pressure to an emergency ausgew position to effect an emergency application of the brakes', said Vvalve device being movable upon an over reduction in pressure at a service rate first to service position and then to emergency position for effecting a service application of the brakes, valve means operative upon a service reduction in brake pipe pressure to effect a service reduction in pressure on said valve device and operative upon an emergency reduction in brake pipe pressure to effect an over reduction in pressure on said valve device, a cut out valve device movable to a position for effecting an emergency reduction in pressure on. said valve device upon an emergency reduction in brake pipe pressure, and means for' limiting the degree of brake application effected by the operation of said valve device, said brake valve device being operative in emergency position for supplying fluid under pressure to increase the degree of 4brake application to, and to maintain the degree of brake application at the setting of said limiting means.

21. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in brake pipe pressure to effect an application of the brakes, and valve means for controlling the operation of said brake controlling Valve device in accordance with variations in brake pipe pressure, said Valve means comprising a reservoir normally charged with fluid under pressure, a timing valve device normally maintained in one position by the pressure of fluid in said reservoir and movable to an application position upon a predetermined reduction in pressure in said reservoir, for reducing the pressure on said brake controlling valve device, and a control valve movable to an application position upon a reduction in brake pipe pressure to establish a communication through which fluid under pressure is vented from 'said reservoir.

22. In a iiuid pressure brake, the combination With a brake pipe, of a brake controlling valve device operative upon a reduction in brake pipe pressure to effect an application of the brakes, .and valve means for controlling the operation of said brake controlling valve device in accordance with variations in brake pipe pressure, said valve means comprising a reservoir normally charged With fluid under pressure, a timing valve device normally maintained in one position by the pressure of fluid in said reservoir and movable to an application position upon a predetermined reduction in pressure in said res- 'ervoir for reducing the pressure on said brake controlling valve device at a service rate, and a control valve movable to an application position upon a reduction in brake pipe pressure to establish a communication through which fluid under pressure is vented from said reservoir, and to establish another communication from said equalizing valve device to said timing valve device through Which fluid under pressure is vented from said equalizing valve device, and a manually operable valve movable to a position for establishing a direct connection from the last mentioned communication to the atmosphere and for cutting off said reservoir from said timing valve device.

23. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in pressure in a chamber to effect an application of the brakes and operative upon an increase in pressure in said chamber to effect a release of the brakes, a. 75

reservoir, a timing valve device operative upon a reduction in -pressure in said reservoir to open a communication through which. fluidr under pressure is vented from said chamber, a control valve device subject to the opposing pressures of said chamberand the brake pipe andoperative upon a reduction in brake pipezpressure to vent fluid under pressure 4from said reservoir and movable kupon an .increase in brake pipe pressure to a normal positionfor opening a communication through which fluid under pressure is supplied from said brake pipe to said chamber, a choke in said communicationV for controlling the rate of supply to said chamber, a ball check valve in said communication, a choke in a passage by-passing said ball check valve and on the chamber side of the `rst mentioned choke for limiting back flow of fluid under pressure from said chamber to said brake pipe upon a brake pipe reduction,V a branch from said communication on the brake pipe side of said first,y mentioned choke for supplying fluid under pressure from said brake pipe to said'reservoir, and Y a choke in said branch for maintaining a pressure head on the first mentioned choke, the communication through said branch to said timing reservoir being opened by said control valve device When in its normal position.

24. In a fluid pressure brake, the combination vvith a brake pipe, and a brake controlling valve device operative upon an increase in the pressure of fluid to effect a release of the brakes and upon a reduction in the pressure of fluid to eect an application of the brakes, of a control valve device operative upon an increase in brake pipe pressure to supply fluid under pressure tol said brake controlling valve device and upon a reduction in brake pipe pressure to cut on the supply of fluid under pressure to said brake controlling valve device, and means controlled by said control valve device and operative upon a service rate and an emergency rate of reduction in brake pipe pressure to reduce the pressure of fluid acting on said brake controlling valve device at a service rate.

25. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in fluid pressure to eiect an application of the brakes, valve means operative upon a reduction in brake pipe pressure, to reduce the pressure on said brake controlling valve device, and means operative to prevent said valve means from effecting such reduction in pressure on said brake controlling valve device for a chosen interval of time after the reduction in brake pipe pressure is initiated.

26. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in fluid pressure to eiect an application of the brakes, valve means operative upon a reduction in brake pipe pressure to reduce the pressure on said brake controlling rvalve device a predetermined time after the reduction in brake pipe pressure is initiated, and means for limiting the rate of reduction in pressure on said brake controlling valve device to a service rate regardless of the rate of reduction in brake pipe pressure.

27. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling valve device operative upon a reduction in uid pressure to effect an application of the brakes, and valve means operative upon a service and an emergency rate of reduction in brake pipe pressure to reduce the pressure on said brake controlling valve device at a service rate, said valve means being also operative to delay the reduction in pressure Aon said brake controlling valve de- .Vice for a predetermined time interval after the reduction in brake pipe pressure is initiated.

Y28. In a fluid pressure brake, the combination with a brake pipe, of a brake controlling ,valve device operative upon a reduction in fluid pressurelto eflectan application of the brakes, l-valve means operative upon a reduction in brake pipe pressure to reduce the pressure on said brake controlling valve device, and means for limiting the rate of reduction in pressure on said brake controlling valve device to a service rate regardless of the rate of brake pipe reduction on said valve means.

29. In a fluid pressure brake, the combination with a brake pipe and a brake cylinder, of a valve device operative by iluid under pressure to supply fluid under pressure to said brake cylinder to elect an application of locomotive brakes, valve means operative to supply iluid under pressure for effecting the operation of said valve device, control means operative upon a reduction in brake pipe pressure, and timing means set in operation upon the operation of said control means, and operative to effect operation of said valve means a predetermined period of time after the reduction in brake pipe pressure is initiated.

30. In aV fluid pressure brake, the combination Vvvith a brake pipe successive reductions in pressure in which' are adapted to effect a graduated application of the brakes, of means on the locomotive responsive to said reductions in brake pipe pressure for effecting a graduated applicay tion of the brakes, and timing means set in operation upon initiating the initial reduction of said successive reductions in brake pipe pressure for delaying the operation of said means for a predetermined period of time after the reduction in brake pipe pressure is initiated, said timing means being inoperative to delay the operationof said means after the initial reduction of said successive reductions.

3l. In a uid pressure brake, the combination with a brake pipe a reduction in pressure in which is adapted to effect an application of the brakes on a train, of valve means on the locomotive operative upon a reduction in brake pipe 'F pressure to effect an application of the locomotive brakes, a valve device set in operation upon initiating a reduction in brake pipe pressure for* delaying the operation of said valve means for an interval of time after the reduction in brake pipe pressure is initiated, and means for varying the length of said interval of time according to the length of the train. y

32. In a fluid pressure brake, the combination with a brake pipe a reduction in pressure in which is adapted to eifect an application of the brakes on a train, of Valve means on the locomotive operative upon a reduction in brake pipe pressure to effect an application of the locomotive brakes, a valve device for delaying the operation oi said valve means for an interval of time after the reduction in brake pipe pressure is initiated, and means adjustable according to the length of the train for varying said interval of time. i

33. In a fluid pressure brake, the combination with a brake pipe a reduction in pressure in Which is adapted to eiect an application of the brakes on a train, of Valve means on the locomotive operative upon a reduction in brake pipe pressure to effect an application of the locomotive brakes, said valve means including a timing reservoir normally charged With fluid under pressure, means for venting fluid under pressure from said timing reservoir, a valve device operative when the pressure in said timing reservoir is reduced to a predetermined degree to effect the application of locomotive brakes, and a manually operated valve device for controlling the Venting of iiuid under pressure from said timing reservoir, said manually operated valve device having a plurality of positions corresponding to different lengths of trains, and means operative in each of said positions for determining the rate at which iiuid under pressureY is vented from said timing reservoir.

ELLIS E. HEWI'I'I. CLYDE C. FARMER.

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